volume: 39, issue: 1
volume: 39, issue: 2
Open-air fires or forest fires are becoming a key factor in reducing the forest surface areas and
they are one of the major factors of devastation and degradation of forests and forest land and
their ecosystems in the Mediterranean, mainly in coastal karst. They cause extreme material
and economic damage, and they negatively affect biological and landscape diversity. After the
forest fire, significant quantities of fired trees are left behind, representing a significant amount
of lignocellulosic biomass available for conversion into a variety of biobased products. The
question arises as to what degree they are chemically degraded, or whether they still have the
properties required for further application in mechanical or chemical processing.
The main aim of this paper was to study the group chemical composition as a biomass chemical
property of the Aleppo pine (Pinus halepensis Mill.) sapwood before and after the impact
of low ground fire and high fire of the treetops at tree height of 0, 2 and 4 m. Therefore, the
impact of forest fires on the Allepo pine sapwood group chemical composition was studied in
terms of quality for further application in production of biorefinery products. In addition,
research results on group chemical composition of the same unfired and fired Aleppo pine wood
bark from previous study were used for comparison with sapwood from this study.
The obtained results show that the distribution of the main chemical components of Aleppo pine
unfired wood bark and sapwood is similar to the results of previous studies for different wood
species. That means that the bark contains a significantly higher content of ash, accessory materials
(extractives) and lignins, and a significantly lower content of polysaccharides cellulose and
polyoses (hemicellulose) than sapwood. The bark results from previous studies show a significant
difference in reduced ash, cellulose and lignin content, and in the increased accessory materials
and wood polyoses (hemicellulose) content between the unfired and fired wood. Furthermore, the
content of individual chemical components of fired bark at different forest fires heights of 0, 2 and
4 m for each sample did not differ significantly. Contrary to fired bark, no significant differences
have been observed in the chemical composition of sapwood between unfired and fired wood, not
even resulting from different forest fires heights. It can be concluded that the forest fire did not
have any effect on Aleppo pine sapwood, where the fired wood bark took over all the damage
caused by high temperature during the forest fire. In addition, the fired sapwood still retains the
chemical properties required for further application in biorefinery biobased products.
volume: 40, issue: 1
The study developed robust benchmark figures for the performance of delimber-debarker-chippers
in fast-growing eucalypt plantations, through the analysis of an exceptionally large database
that combined automatically-captured and user-input records. Data for three Peterson
Pacific DDC 5000 H units operated by the Brazilian company Fibria Cellulose were captured
continuously for three years, from 2015 to 2017. During this time, all study machines ran
triple-shift and clocked over 25 000 hours each. The consolidated record included information
for 79 858 delay events, with an average duration of 0.55 hours per event. Delay time accounted
for 57% of total worksite time: mean utilization was therefore 43%. Maintenance was
the most important cause of delays, and accounted for 22% of total worksite time. Interaction
delays came second, and represented 20% of total worksite time. Mean productivity was
88 solid m3 ub (under bark) per productive machine hour (PMH) or 39 solid m3
ub per scheduled machine hour (SMH), depending on whether delay time was excluded or included in the
calculation. The gap between the most efficient and the least efficient operator was 22% and
26% for scheduled productivity and utilization, respectively (this difference was calculated by
taking the figures for the lowest performer as a basis). While the exact productivity figures
reported here may reflect the exceptionally favorable conditions encountered in rationallymanaged
South American plantations, the dynamics revealed in this study may have general
validity and could offer precious insights for rationalizing a whole range of similar operations.
volume: 40, issue:
The goal of the research was to determine the biomass yield and fuel properties of ten different poplar clones. The research was conducted in an experimental plot established in Forest Administration Osijek, Forest Office Darda, in the spring of 2014. The layout of the plot consisted of three repetitions per clone with 40 plants per repetition in spacing 3x1 m. Based on the DBH distribution, in the early spring of 2018, one sample tree of an average DBH per repetition was selected, thus forming a sample of 30 trees.
Average survival rate of the investigated trees after four vegetation periods was 74.54 ±13.85% ranging from 52.08% (Koreana) to 91.67% (SV885 and SV490). Average DBH of the sample trees was 8.2 ±1.9 cm, height 9.3 ±1.8 m and root collar diameter 10.7 ±1.9 cm. Moisture content in fresh state (just after the felling) ranged from 51.6% (Hybride 275) to 55.9% (SV885). Bark content averaged 18.4%, from 15.4% (Baldo) to 21.1% (V 609). Average nominal density of the sampled trees amounted to 383.5 ±35.9 kg/m3. Bark ash content was on average ten times higher (6.44 ±0.65%) than wood ash content (0.64 ±0.07%) resulting in average ash content of 1.7 ±0.1% (taking the bark content into account).
The clone SV490 showed the highest biomass yield with 15.8 t/ha/year, while the lowest biomass yield was recorded for the clone Hybride 275 with 2.8 t/ha/year.
High inter-clonal productivity variation stresses the importance of selection work to find the most appropriate clones with the highest productivity potential for the given area where the poplar SRC plantations are to be established.
Due to high initial moisture content, if direct chipping harvesting systems are preferred, wood chips could be efficiently used in CHP (Combined Heat and Power) plants that operate on the principle of biomass gasification (where a gasifier is coupled to a gas engine to produce electric power and heat). In several CHP gasification plants operating in Croatia, wood chips with high initial moisture content (from traditional poplar plantations) are used as a feedstock that has to be pre-dried using the surplus heat. In this respect SRC poplar wood chips could make an ideal feedstock supplement.
volume: 41, issue: 1
A chain-flail delimber-debarker-chipper (CFDDC) was adapted for treating smaller trees than normal by replacing the standard flails with lighter ones, and by reducing flail drum rotation speed. The machine produced 16 full containers (24 t each) for the standard configuration and 24 full containers for the innovative one. For each container the researchers measured: original tree mass, chip mass, time consumption and fuel use. Results indicated that the innovative setting accrued a 12% improvement on fiber recovery compared with the standard setting (control). At the same time, productivity increased by 20% and fuel consumption was reduced by 30%. Product quality was largely unaffected, with bark content remaining below the 1% threshold specification. If at all, product quality was improved through the reduction of fine particles, possibly derived from less diffused fraying. These results have triggered the real scale adoption of the new setting by contractors who participated in the study. The success of the innovative treatment is likely explained by its better alignment with the weaker structure of small trees from low-yielding stands.
volume: 41, issue:
To make forest biomass more competitive, increased efficiency in the handling and supply system is needed, thus producing high-quality fuel at a lower cost. Operating costs can be reduced if the target chip size is increased, as this increases productivity and reduces chipper fuel consumption. However, the chips need to be storedin order to meet fluctuating seasonal demand and maintain high machine utilisation. Due to biomass degradation, storage of comminuted biomass can lead to high energy losses, but can also increase fuel quality, e.g. by reducing moisture content and increasing net calorific value. This study evaluated the effects of storage on dry matter losses and differences in fuel quality of the stored biomass for three target chip sizes and three materials during six months of storage. The results showed that coarse chips had significantly lower moisture content and lower energy losses after storage than fine chips. Overall, changes during storage resulted in an economic loss of 3–4% per oven-dry ton for fine chips, but an economic gain of 2–6% for coarse chips. Thus increased target chip size can increase the competitiveness of forest biomass through decreased production costs and reduced storage costs. It can also ensure higher, more consistent fuel quality.